Power unit



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Temperaure -Abs- F Patented Dec. 19, 1950 UNITED sTATEs PATENT oFFicE POWER UNIT Fred P. Gerhardt, Milwaukee, Wis.

Application June 12, 1947, Serial No. 754,190

(CL 12S-53) Claims. l

This invention relates to power units or prime movers and in general is designed to provide a power unit of the type shown in and which is an improvement on the power unit covered by my prior United States patent, No. 2,398,221, dated April 9, 1946.

The general objects of the invention are to provide a power unit driven by internal combustion which Will have a greatly increased eiflciency as compared with the most efficient internal combustion engines known today; to provide a power unit having a high ratio of expansion to compression; to provide a construction in which the gases of expansion not only work on the piston in the combustion chamber but also work against the pistons compressing air for succeeding charges in the cylinders; and to provide a power unit in which each combustion is so divided that approximately half the energy is exerted in one direction and half in the opposite, 180 apart, so as to obtain a perfect balance of the power thrust on the engine shaft. I also aim to conserve a large proportion of the heat (B. t. u.s) ordinarily lost by radiation or in the cooling system or in the exhaust, and to convert this heat into power. Further objects are to provide a power unit of enhanced efciency adapted to burn gasoline, kerosene, fuel oil or powdered coal, which develops higher power in proportion to the amount of fuel used, and which may be used as a marine engine, an automotive power plant, a radial aircraft engine, and fo!` all other purposes for which an internal combustion engine may be used. Other objects in view will also appear in the course of the subjoined description.

In the accompanying diagrammatic drawings:

Fig. 1 is a longitudinal sectional view through a power unit embodying my invention, showing the power pistons of the primary and secondary sets of pistons just after the beginning of their power and charge compressing strokes, respectively, and the other parts in their coordinating positions Fig. 2 is a similar view showing the power pistons of the secondary and primary sets of pistons just after the beginning of their power and charge compressing strokes, respectively, and the other parts in their coordinating positions;

Fig. 3 is a chart diagram showing the abscissas and coordinates in temperatures and volumes on an expansion stroke in a working operation of the power unit as compared with the developments, for example, in a normal Diesel engine; and

Fig. 4 is asection ontheline l-lofFlg. 1.

Referring now more particularly to Figs. 1 ana 2 of the drawings, wherein I show the invention as embodied in a two-cycle compound unit, employing two sets of cylinders and pistons, each ot three-stage air compression type, A represents a low compression chamber or cylinder, B an intermediate compression chamber or cylinder, and C a high pressure chamber or cylinder of the rst set, which chamber C also forms the combustion chamber of that set; and A', B' and C represent the companion chambers or cylinders of the second set. Fixed to a piston rod D mounted to reciprocate in the chambers A, B and C are pistons E, F and G, movable in the respective chambers, and fixed to a piston rod D' mounted to reciprocate in chambers A', B' and C' are pistons E', F and G' movable respectively in these chambers. The sets` of chambers are arranged in parallel relation and the pistons G and G' are responsive alternately to explosions at the inner ends of cylinders C and C' for opposite working strokes. While these explosions may take place as the result of a spark acting on a full charge delivered by a carbureter, I prefer to use liquid fuel injectors H, H' at the inner ends of the cylinders C, C', each injector being of a type known in the art of Diesel engines. 'I'he mechanism by which a measured amount of fuel is delivered at the proper instant to each injector is not shown, as it may be any of several types and as it forms no part of the present invention. The compression cylinders of eachset are axially alined and the low compression cylinder of each set is larger than the associated intermediate cylinder, and each of said cylinders larger than the associated high compression and power cylinder, but the sizes of these cylinders and their relative sizes may vary, as may be found most desirable or efiicient in the construction of a unit of any determined size and power. The cylinders of the respective sets are sealed off at their adjacent ends by heads a, b and c, a', b' and c', and the heads b, c and b', c' between the cylinders A and B and the cylinders A' and B include wall portions I, J, I', J', the walls I and I' being formed with inlet ports e, f and e', J" communicating respectively with said cylinders A, B, A' and B.

The chambers or cylinders of each set are provided with air supply and spent gas exhaust ports and air and gas iiow pipe or passage connections between each other and between the chambers of the sets as follows: each cylinder A, A' has at its forward end a check valved air inlet k, k' and a check valved air outlet l, l', and each has at its rear end a check valved gas exhaust outlet m, m', the outlets l, l of said cylinders being in communication through pipes or passages n, n with the rear ends of cylinders B and B'. Each cylinder B. B' has a check valved gas exhaust outlet-0,70' at its forward end and said cylinders are respectively in communication at their rear ends through check valved gas supply pipes p, P' with the forward ends of chamber C, C'. The chambers C, C have front gas exhaust outlets controlled by check valves V, V and rear gas exhaust outlets connected with check valved pipes or passages r, r which are in turn connected with the front exhaust outlets and with each other and also with exhaust pipes v and v' by a cross pipe or passage s. The wall portions I, I',

' J, J of the heads b, c; b', c' are provided with curved surfaces or cavities t for cooperation with curved surfaces or cavities t' formed in the opposed faces of pistons E, F, G, E', F', G'. The inlet ports e, f communicate, respectively, with the rear end of chamber A and front end of chamber B, while the inlet ports e', f' communivalve w controlling the discharge of burning spent gases and air through a jet pipe a: to jet propulsion nozzles or to a turbine to be driven or to secure fast expansion in the cylinders. Auxiliary fuel injectors I-I and H" are provided to inject fresh fuel into the gases owing through pipes or passages v, o' to maintain combustion and increase the thermal eiliciency of these gases by increasing their expansion and reducing their temperature drop.

Fig. 1 shows the position of the parts which they occupy when piston G hasy completed its charge compressionstroke and 'has started its working stroke, and in which piston G' is starting its compression stroke, the other pistons and valves being shown in their proper relative positions for performing their respective functions. With this understanding the operation is as follows:

The air is first drawn into cylinder A through port lc on the inward stroke of piston E (working stroke of piston G), and this air in cylinder A is compressed and discharged on the succeeding outward-stroke oi' piston E through pipe n into the rear end of cylinder B, so that on the inward or backward stroke of piston F it will be further compressed in cylinder B and forced through pipe p into forward end of cylinder C. in which it is compressed still further ony the forward compression stroke of piston G and fired when the fuel is injected by injector H at the end of such stroke of piston G. -Thus the air is compressedl in three stages and at the end of h: third stage is mixed with the injected fuel and When the charge in cylinder C is red and the piston G is moving outward on its working stroke under pressure of the expanding gases, portions of the gases iiow from cylinder C through pipes v, v' and u' and ports f, e' to the outer end of cylinder B behind piston F and to the inner end of cylinder A' behind piston E', which pistons are compressing air for succeeding charges and in which the gases expand to assist piston G on its working stroke and to move piston 'G' inward on its high compression stroke. At the same time pistons E and F', which are in suction, drawing air respectively through inlet k of cylinder A and pipe n' of cylinder B', are forcing mixed air and spent gases therein outward through valve m of cylinder A and valve o of cylinder B'. Thus expansion of the combustion gases and air takes place in three chambers C, B and A' of relative areas such as to apply equal or substantially equal forces on the pistons G, G' to move them in opposite directions. While piston G is on its working stroke and piston G' on its high compression stroke cylinder A is in low pressure suction, cylinder B in intermediate stage compression. cylinder A' in low compression and cylinder B in intermediate suction. When piston G reaches the end of its working stroke and begins its compression stroke, piston G' starts its working stroke on the injection of fuel by injector H' and the firing of the charge in cylinder C', and the working operations of the two sets of cylinders and pistons are reversed, as will be readily understood. Also, the suction, compression and exhaust actions in the sets of cylinders will be evident from the foregoing description.

It will be observed that this engine is composed oi' two interconnected sets of cylinders, each having three compartments with a tandem piston in each compartment, as shown.

The engine is a. 3-stage compressor and C. l. engine, the largest compartment or sub-cylinder being the first stage, the central compartment being the second stage. and the smallest and bottom compartment being the third stage compressor `and preliminary ignition and combustion chamber.

They are interconnected by pipes and valves as indicated, although many other pipe and valve arrangements can be made and the number ofcompartments reduced to achieve the same or related purposes. The action and operation of each set of cylinders may be accomplished in some cases without the use of the compartments B, B'.

To more specifically set forth the operation of the engine, it will be seen that air is drawn] into cylinder A or A' at the top on down stroke,

compressed on up stroke and discharged through pipe n or n' into compartment B or B' below the piston therein. On the next down stroke this air is further compressed and then discharged through pipe p or p' into compartment ,1

C or C', where it is further compressed on the next up stroke. At the top or nish of the third j compression, fuel is'injected into this high pressure chamber C or C' through injector H or H' and fuel is also injected into the high pressure air as it issues from said chamber through valve '4 V or V' by means of injector Hl or H. The

major part of the 'fuel is injected by injector H* or I-I' located in pipe v or pipe v'. Enough fuel is injected by injector H or H to keep up the pressure in the chamber C or C' so that a fast ilow of burning fuel and air can be maintained through pipe v or v' into the expansion and stretched out by the fast moving air charge.

amato and in this way the complete charge of air and fuel are mixed together proportionately as fast as fuel is taken from the tip of the injector.

This charge of fuel and air, starting from chamber C or C expands not only in chamber C but also into and in chamber A (below piston) and into and in chamber B (above piston), and simultaneously in all three chambers.

In this engine there are always three complete air charges being compressed while only one is being burned and expanded into a volume equal to that containing the three volumes under compression. In this way the expansion ratio is inherently much greater than the compression ratio no matter what the compression ratio happens to be. In the diagram shown this ratio is about as 2 is to 1. This ratio can easily be increased or decreased. Being a stage compressor as well, the length of stroke can also be a normal length or less or made to coordinate with the diameter of cylinders, and amounts of air and compression pressures desired.

This does not only mean merely a larger expansion ratio to compression ratio but in addition, because the stroke is not necessarily increased in length, a much greater rate of temperature decrease during expansion. This is very clearly shown by the comparison of temperature curves at the bottom of the diagram in Fig. 3. The temperature losses are therefore obviously greatly reduced, and with the gases working on three pistons and expanding simultaneously in three chambers, the heat saved has ample opportunity to be changed into work.

The cranks of the sets` of cylinders being set 180 apart on the shaft, each burning charge divides its power (say in half) as shown on the diagram so that a turning couple is exerted on the shaft by each charge.

There are two charges burned in this way during each revolution, ilrst starting from cylinder A and then from cylinder A'. There is therefore a continuous turning moment on each crank and rod. This engine, although a piston and cylinder engine will run very smooth and evenly and require little or no balance weights or flywheel.

Furthermore, since each power thrust is divided between two cranks and rods the bearings need be only half as large per horsepower and the moving parts only half as large or heavy per shaft horsepower. In other words, the power thrust is divided and distributed amongst the moving parts more evenly per revolution instead of being concentrated on one thrust and one crank per revolution.

These factors all greatly increase the ability of the engine to run at high speeds because the weight of the moving parts of an engine largely determine the speed the engine can run at.

The acceleration is proportional directly to the "accelerating" force and inversely to the mass, or inertia, of the moving body.

The large amounts of air with their fuel Y charges at high pressures also mean a great increase in M. E. P. or accelerating force.

The pressures o1' the expanding or burning gases are rst reduced by expansion in the lnozzles in the cylinder heads (but increasing the velocity) thereby permitting lighter cylinder construction and lighter 'piston construction as shown, the central part ofthe larger pistons taking the impact The force due to impact is partly turned into work against the pistons as shown and Partly back into heat and pressure.

This drop in pressure through nozzles into the larger compartments with its resultant velocity of gases can be made use of in overcoming inertia at the beginning of the stroke by deecting the gases back and forth through and at each second deiiection striking the pistons. Turbine action can be obtained by using a number of so-called stages of deection; for instance, with the gas entering at a speed of 1000 feet per second and piston speed 50 feet per second, there would have to be marl deflections back and forth in order to use up all the kinetic energy.

The necessary curved surfaces could easily be constructed on large pistons and heads, and a variable speed compound turbine principle applied to the pistons and heads. This would then permit very light piston and cylinder construction for chambers I and 2. Without this feature only a small length of the cylinders need be built thick.

'Ihen also, the gases of combustion are not all shot into these chambers at one distance, but from a pipe and during a denite period of time, which fact spreads the effect of shock or impact throughout the action and reduces its intensity greatly. The acceleration would be greatly increased.

'I'he diagram in Fig. 3 shows a set of pressurevolume curves for the compartments A, B and C. The lower part of the curves shows the air compression side of the pistons and the upper part of the curves shows the expansion or working side oi the pistons. The one for chamber C (the smallest) shows both parts as taking place on the same side of the piston. Chamber C is ilnally exhausted through lowest pipe shown by the incoming air charge.

'I'he entropy diagram as well as the others are very significant and show a very close approximation for a given design. The range of designs and results is almost unlimited, with all basic factors pointing to greatly increased eiliciencies and power outputs. With the resultant low average temperatures, the need of cooling water would be practically eliminated,

especially when the design is used as a jet engine with its extreme speed possible in changing heat into work. Most any burning pressures may be used to start, say from 500 pounds up.

From the foregoing description the construction and mode of operation of my improved power unit will be readily understood without a further and extended description. While the construction exemplificatively shown is preferred, it is to be understood, of course, that changes in the form, construction and arrangement of parts may be made, within the scope of the appended claims, without departing from the spirit or sacriiicing any of the advantages of the invention.

Having thus described my invention, I claim:

1. A power unit of the character described comprising a power cylinder, a compression cylinder, pistons in said cylinders, said cylinders and pistons being arranged in tandem, a rod connecting said Pistons for simultaneous movement in the same direction, means for admitting air to the compression cylinder and conducting air compressed by the piston therein to the power cylinder, means for injecting fuel into the power cylinder and firing a charge of fuel and air therein at the end of the compression stroke of the power piston, and means for conducting gases of combustion resulting from the ring of the charge in the power cylinder to the compression cylinder for the action of the expanding gases on the pistons in both cylinders to cause the piston in the compression cylinder to force compressed air therefrom into the power cylinder during the movement of the power pisy ton on its power stroke.

2. A power unit of the character described comprising two sets of tandem cylinders and pistons. each including a power cylinder and a compression cylinder cooperating therewith, pistons in said cylinders, a rod connecting the piston in each power cylinder and the piston in the associated compression cylinder to move in unison and the respective sets of pistons being arranged for movement simultaneously in opposite directions and for timed cylinder operations at 180 apart, means operating at a proper time period in the cycle of operation of each set for admitting air to the compression cylinder of said set for compression by the piston therein and conducting the compressed air to the power cylinder of said set, means for admitting fuel to the power cylinder of each set at a proper time period in the cycle of operation of each set and ring the charge of fuel and air compressed therein, and means for conducting gases of combustion resulting from the firing of the charge in and acting on the piston in the power cylinder of each set to the compression cylinder of said set for moving the power and compression pistons thereof in one and the same dii rection and also to the compression cylinder of the other set to move the pistons of the latter set in the opposite direction.

3. A power unit of the character described comprising a. power cylinder, a plurality of compression cylinders, pistons in said cylinders, said cylinders and pistons being arranged in tandem,

a rod connecting the pistons to move in the same direction in unison, means for admitting air to one of the compression cylinders, means for conducting air successively from the compression cylinders to the power cylinder, means for admitting fuel to the power cylinder and ring a compressed charge of air and fuel therein, and means for coni ducting gases of combustion resulting from the arranged in tandem, each set including a power cylinder, a low and an intermediate compression cylinder cooperating with said power cylinder, pistons in said cylinders, and a rod connecting the piston in each power cylinder and the pistons in the associated compression cylinders to move in unison in the same direction, the sets of pistons being arranged ior timed similar operations at apart, means for admitting air to a compression cylinder of either set for compression by the piston therein and conducting the compressed air to the intermediate compression cylinder so as to cause the piston therein to force the compressed air into the power cylinder of said set during the movement of the power piston on its working stroke, means for admitting fuel to each power cylinder and firing the charge of fuel and air compressed therein, and means for conducting gases of combustion resulting from the ring of a charge acting on the piston of a power cylinder of a set to the intermediate compression cylinder of said set for moving said pistons in unison in one direction and also to the low compression cylinder of the other set to move the pistons of said set in the opposite direction, said means including an exhaust pipe leading from each power cylinder to the intermediate compression cylinder of its set and the low compression cylinder of the other set and a pipe connection between said exhaust pipes.

5. A power unit of the character described comprising a power cylinder, a compression cylinder, pistons in said cylinders, said pistons being arranged in tandem, and a rod connecting the pistons for movement lin unison in the same direction, means for admitting air to the compression cylinder and conducting air compressed by the piston therein to the power cylinder, means for admitting fuel to the power cylinder and firing a compressed charge of fuel and air therein. conducting means for conducting gases of combustion resulting from the firing of the charge in the power cylinder to the compression cylinder for the action of the expanding gases on the pistons in both cylinders so as to cause the piston in the compression cylinder to force compressed air therefrom into the power cylinder on the working stroke of the power piston, and means for admitting fuel to said conducting means for admixture and combustion with the gases flowing therethrough.

FRED P. GERHARDT.

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UNITED STATES PATENTS Number Name Date 567,530 Willetts Sept. 8, 1896 806,195 DeSanderval Dec. 5, 1905 1,175,395 Wixon Mar. 14, 1916 1,603,256 4 Dunham Oct. 12, 1926 1,623,798 Limont Apr. 5, 1927 1,819,825 Poyer Aug. 18, 1931 1,881,789 Mantle Oct. 11, 1932 1,892,635 Schwarz Dec. 27, 1932 2,182,063 Steiner Dec. 5, 1939 2,189,106 Garve Feb. 6, 1940 2,409,176 Allen Oct. 15, 1946 2,411,227 1946 Planiol Nov. 19, 

